Technological Field
The present disclosure relates to methods for electrically connecting electrically conductive threads or yarns integrated with textile, more in particular for electrically connecting crossing conductive threads or yarns in a textile layer.
The present disclosure further relates to textile fabrics or textile layers containing electrically conductive threads or yarns, and containing at least one electrical connection between crossing conductive threads or yarns.
Description of the Related Technology
Integration of electronic devices or electronic circuits with textile can add new functionalities to the textile, allowing the realization of for example, clothes with integrated sensors, luminous textile or wearable computing.
When integrating electronic circuitry with textile, there is also a need for routing signals between various devices. The devices may be distributed over an area of the textile, and they may interact with each other through electrically conductive threads or yarns in the textile. This requires the establishment of electrical connections between crossing electrically conductive threads or yarns, for example for electrically connecting power lines, ground lines or data lines integrated in the textile.
Electrically connecting crossing electrically conductive threads can for example be obtained by soldering or by welding at the crossover points. However, such electrical connections may have a limited mechanical strength and, especially when provided in an elastic or stretchable fabric, they may be damaged or broken as a result of stretching of the fabric or textile.
In “Fundamental Building Blocks for Circuits on. Textiles,” IEEE Transactions on Advanced Packaging, Vol. 30, No. 3, August 2007, I. Locher et al. describe a manufacturing technology for establishing arbitrarily-connected wiring structures within a fabric containing a mesh of copper wires coated with an electrical insulation material. Such wiring structures consist of single interconnects between copper wires and are called “textile via's.” Forming a textile via according to this technology comprises removal of the coating from the copper wires at predefined yarn intersections, and interconnection of the skinned wire sections by dispensing a drop of conductive adhesive on the skinned spot, thereby electrically connecting two crossing wires. The mechanical reliability of this structure is rather poor, and therefore an epoxy resin is deposited on the connection, to add mechanical and electrical protection. This results in relatively large epoxy features on the textile, which may locally affect the textile properties (e.g. stretchability) in an undesired way, and which may result in a visually unattractive product, being in conflict with the concept of “disappearing electronics” in smart textiles.